Virtual aggregation of fragmented wireless spectrum

ABSTRACT

Method and apparatus for aggregating spectrum in which multiple disjoint blocks of spectrum may be configured as one virtual contiguous block of spectrum by modulating onto each disjoint blocks of spectrum a respective portion of a data stream in which the data rate associated with the modulated portion is compatible with the available bandwidth of the disjoint spectrum block upon which is modulated.

FIELD OF THE INVENTION

The invention relates generally to communication networks and, morespecifically, but not exclusively, to satellite- and microwave-basedpoint-to-point communication and backhaul links.

BACKGROUND

Traditional wireless systems assume the availability of a contiguousblock of spectrum with bandwidth proportional to the amount of data tobe transmitted. Transmission systems are thus frequently designed forworst-case bandwidth requirements with the typical or average use-case,in some instances, requiring much less bandwidth (i.e., spectrum).

Within the context of satellite communications systems and otherpoint-to-point communications systems, available spectrum allocated tocustomers may become fragmented over time, which leads to unused blocksbetween allocated blocks of spectrum. When the blocks of unused spectrumare too small, it is necessary to reallocate spectrum among customers or“move” a customer from existing spectral allocation to a new spectralallocation so that the unused blocks of spectrum may be coalesced into asingle spectral region. Unfortunately, such reallocation is verydisruptive.

BRIEF SUMMARY

Various deficiencies of the prior art are addressed by the presentinvention of systems, methods and apparatus aggregating spectrum inwhich multiple disjoint blocks of spectrum may be configured as onevirtual contiguous block of spectrum by modulating onto each disjointblocks of spectrum a respective portion of a data stream in which thedata rate associated with the modulated portion is compatible with theavailable bandwidth of the disjoint spectrum block upon which ismodulated.

A method according to one embodiment comprises dividing a data streaminto a plurality of sub-streams, each of the sub-streams associated arespective spectral fragment and having a data rate compatible with abandwidth of the respective spectral fragment; modulating each of thesub-streams to provide a modulated signal adapted for transmission viathe respective spectral fragment; and upconverting the modulated signalsonto respective spectral fragments of at least one carrier signal;wherein the sub-streams included within the upconverted modulatedsignals are adapted to be demodulated and combined at a receiver torecover thereby data stream.

An apparatus according to one embodiment comprises a splitter, fordividing a data stream into a plurality of sub-streams, each of thesub-streams associated a respective spectral fragment and having a datarate compatible with a bandwidth of the respective spectral fragment; aplurality of modulators, each modulator configured to modulate arespective sub-stream to provide a modulated signal adapted fortransmission via the respective spectral fragment; and at least oneupconverter, for upconverting the modulated signals onto respectivespectral fragments of at least one carrier signal; wherein thesub-streams included within the upconverted modulated signals areadapted to be demodulated and combined at a receiver to recover therebydata stream.

The splitting function of the method or apparatus may includeencapsulating sequential portions of the data stream into payloadportions of respective encapsulating packets, each of the sequentialportions of the data stream being associated with a respective sequencenumber included within a header portion of the respective encapsulatingpacket; and selectively routing encapsulated packets towardsdemodulators.

The selective routing may be based on routing encapsulating packetsaccording any of a random routing algorithm, a round robin routingalgorithm, a customer preference algorithm, a service providerpreference algorithm and so on where each sub-stream is associated witha respective weight.

The various sub-streams may be modulated and up converted onto a carriersignal for transmission via one or more transponders within a satellitemedication system, one or more microwave links within a microwavecommunications system and/or one or more wireless channels within awireless communication system.

In various embodiments, encapsulated packets are routed multiple timesto add resiliency/redundancy.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts a block diagram of a communication system according toone embodiment;

FIG. 2 depicts a graphical representation of a spectral allocationuseful in understanding the present embodiments;

FIG. 3 depicts a high-level block diagram of a general purpose computingdevice suitable for use in various embodiments;

FIGS. 4-6 depicts flow diagrams of methods according to variousembodiments;

FIGS. 7-9 depicts block diagrams of communication systems according tovarious embodiments;

FIG. 10 depicts a high-level block diagram of a slicer/de-multiplexersuitable for use in various embodiments; and

FIG. 11 depicts a flow diagram of a method according to one embodiment.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be primarily described within the context of asatellite communications system. However, those skilled in the art andinformed by the teachings herein will realize that the invention is alsoapplicable to any system benefiting from flexible spectral allocation,such as microwave communications systems, wireless communicationssystems and the like.

One embodiment provides an efficient and general-purpose technique foraggregating multiple, fragmented blocks of wireless spectrum into onecontiguous virtual block such that the cumulative bandwidth is almostequal to the sum of the bandwidths of the constituent blocks. Thefragmented blocks are optionally separated from each other by blocks ofspectrum, such as guard blocks, blocks owned by other parties, blocksprohibited by the wireless spectrum regulatory authority of a region orcountry and so on.

FIG. 1 depicts a block diagram of a communication system benefiting fromvarious embodiments. The communication system 100 of FIG. 1 comprises apoint-to-point link including a virtual spectrum aggregator transmitter110, a power amplifier 120, a satellite uplink 130, a satellite 140, asatellite downlink 150, a virtual spectrum aggregator receiver 160 and,optionally, a control module 170. Data to be transmitted over thepoint-to-point link is provided as a stream of data packets D, such as188-byte transport stream (TS) packets, 64-1500 bytes Ethernet packetsand so on. The specific packet structure, data conveyed within a packetstructure and so on is readily adapted to the various embodimentsdescribed herein.

The input data stream D is received by the virtual spectrum aggregatedtransmitter 110, where it is processed by a slicer/demultiplexer 111 toprovide N sub-streams (D₀ . . . D_(N−1)), where N corresponds to anumber of spectral fragments denoted as S₀, S₁ and so on up to S_(N−1).

As depicted in FIG. 1, N=3 such that the slicer/demultiplexer 111slices, the multiplexes and/or divides the input data stream D into(illustratively) three sub-streams denoted as D₀, D₁ and D₂.

Each of the sub-streams D₀, D₁ and D₂ is coupled to a respectivemodulator 112 (i.e., modulators 112 ₀, 112 ₁ and 112 ₂). Each of themodulators 112 ₀, 112 ₁ and 112 ₂ modulates its respective sub-streamD₀, D₁ and D₂ to provide corresponding modulated signals to be carriedby respective spectral fragments S₀, S₁ and S₂.

The modulators 112 may comprise modulators having the samecharacteristics or having different characteristics, such as thecharacteristics of waveform type, constellation maps, forward errorcorrection (FEC) settings and so on. Each modulator may be optimizedaccording to a specific type of traffic (e.g., streaming media,non-streaming data and the like), the specific channel conditionsassociated with its corresponding spectral fragment S_(i) and/or othercriteria.

Generally speaking, the amount of data allocated by theslicer/demultiplexer 111 to any sub-stream D_(i) is proportional to thedata carrying capacity of the corresponding spectral fragment S_(i). Invarious embodiments, each of the sub-streams D_(i) comprises the sameamount of data, while in other embodiments the various sub-streams D_(i)may comprise different amounts of data.

As depicted in FIG. 1, the first modulator 112 ₀ provides a 6 MHz signalassociated with a first spectral fragment S₀; the second modulator 112 ₁provides a 1 MHz signal associated with a second spectral fragment S₁;and third modulator 112 ₂ provides a 1 MHz signal associated with athird spectral fragment S₂.

A frequency multiplexer (i.e., signal combiner) 113 operates to combinethe modulated signals to produce a combined modulated signal S_(C),which is modulated onto a carrier signal by up-converter 114 to providea modulated carrier signal C. It is noted that multiple frequencymultiplexers/signal combiners 113 may be used to multiplex respectivegroups of modulated signals to be transported via common transponders,microwave links, wireless channels and the like.

In the embodiment of FIG. 1, the spectrum associated with the modulatedcarrier signal C is logically or virtually divided into the plurality ofspectral fragments used to convey the modulated data sub-streams. Thespectral fragment allocation table or other data structure is used tokeep track of which spectral fragments have been defined, which spectralfragments are in use (and by which data sub-streams), and which spectralfragments are available. Generally speaking, eachtransponder/transmission channel may be divided into a plurality ofspectral fragments or regions. Each of these spectral fragments orregions may be assigned to a particular data sub-stream. Each of thedata sub-streams may be modulated according to a unique or commonmodulation technique.

As depicted in FIG. 1, a single satellite transponder is used and,therefore, all of the modulated signals may be combined by frequencymultiplexer 113 prior to up-conversion and transmission via a singlesatellite channel. In various embodiments, multiple transponders withinone or more satellites may be used. In these embodiments, only thosemodulated signals to be transmitted via a common transponder within asatellite are combined and then converted together. In variousembodiments, modulate waveforms are transmitted independently.

The modulated carrier signal C produced by up-converter 114 is amplifiedby power amplifier 120 and transmitted to satellite 140 via satelliteuplink 130. Satellite 140 transmits a modulated carrier signal includingthe modulated sub-streams D₀, D₁ and D₂ to satellite downlink 150, whichpropagates the signal to the virtual spectrum aggregator receiver 160.

Virtual spectrum aggregator receiver 160 includes a downconverter (165)which downconverts a combined spectral fragment signal S_(C)′ from areceived carrier signal C′, and a frequency demultiplexer (164) whichoperates to separate the spectral fragments S₀′, S₁′ and S₂′ from thecombined spectral fragment signal S_(C)′.

Each of the spectral fragments S₀′, S₁′ and S₂′ is coupled to a separatedemodulator (i.e., demodulators 162 ₀, 162 ₁ and 162 ₂). Each of thedemodulators 162 ₀, 162 ₁ and 162 ₂ demodulates its respective spectralfragments S₀′, S₁′ and S₂′ to provide corresponding demodulatedsub-streams D₀′, D₁′ and D₂′.

The demodulated sub-streams D₀′, D₁′ and D₂′ are processed by a combiner161 to produce an output data stream D′ representative of the input datastream D initially processed by the virtual spectrum aggregatortransmitter 110. It is noted that each of the demodulators 162 operatesin a manner compatible with its corresponding modulator 112.

Optionally, virtual spectrum aggregator receiver 160 includes buffers166 ₀, 166 ₁ and 166 ₂ which provide an elastic buffering function forthe various demodulated sub-streams such that alignment errors inducedby different propagation delays associated with the various sub-streamsmay be avoided prior to combining the sub-streams. The buffers in 166are depicted as functional elements disposed between the demodulators(162) and combiner 161. In various embodiments, the buffers 166 or theirfunctional equivalent are included within the combiner 161. For example,combiner 161 may include a single buffer which receives data from all ofthe demodulators (162) and subsequently rearranges that data as outputstream D′. Packet ID and/or other information within the sub-streams maybe used for this purpose.

Optional control module 170 interacts with an element management system(EMS), a network management system (NMS) and/or other management orcontrol system suitable for use in managing network elementsimplementing the functions described herein with respect to FIG. 1. Thecontrol module 170 may be used to configure various modulators,demodulators and/or other circuitry within the elements described hereinwith respect FIG. 1. Moreover, the control module 170 may be remotelylocated with respect to the elements controlled thereby, locatedproximate transmission circuitry, located proximate receiver circuitryand so on. The control module 170 may be implemented as a generalpurpose computer programmed to perform specific control functions suchas described herein. In one embodiment, control module 170 adapts theconfiguration and/or operation of the virtual spectrum aggregatortransmitter 110 and the virtual spectrum aggregator receiver 160 via,respectively, a first control signal TXCONF and a second control signalRXCONF. In this embodiment, multiple control signals may be provided inthe case of multiple transmitters and receivers.

FIG. 2 depicts a graphical representation of a spectral allocationuseful in understanding the present embodiments. Specifically, FIG. 2graphically depicts a 36 MHz spectral allocation in which a firstcustomer is allocated a first portion 210 of the spectrum,illustratively a single 10 MHz block; a second customer is allocated asecond portion 220 of the spectrum, illustratively single 8 MHz block; athird customer is allocated a third portion 230 of the spectrum,illustratively single 10 MHz block; and a fourth customer is allocatedis allocated a fourth portion 240 of the spectrum, illustratively threenoncontiguous spectrum blocks comprising a first 1 MHz block 240 ₁, asecond 1 MHz block 240 ₁ and a 6 MHz block 240 ₃.

Within the context of the various embodiments discussed herein, the datastream associated with the fourth customer is divided into two different1 MHz spectral fragments in a single 6 MHz spectral fragment, each ofwhich is processed in substantially the same manner as described abovewith respect to FIG. 1.

FIG. 3 depicts a high-level block diagram of a general purpose computingdevice 300 suitable for use in various embodiments described herein. Forexample, the computing device 300 depicted in FIG. 3 may be used toexecute programs suitable for implementing various transmitterprocessing functions, receiver processing functions and/or managementprocessing functions as will be described herein.

As depicted in FIG. 3, the computing device 300 includes input/output(I/O) circuitry 310, a processor 320 and memory 330. The processor 320is coupled to each of the I/O circuitry 310 and memory 330.

The memory 330 is depicted as including buffers 332, transmitter (TX)programs 334, receiver (RX) programs 336 and or management programs 338.The specific programs stored in memory 330 depend upon the functionimplemented using the computing device 300.

In one embodiment, the slicer/demultiplexer 111 described above withrespect to FIG. 1 is implemented using a computing device such as thecomputing device 300 of FIG. 3. Specifically, the processor 320 executesthe various functions described above with respect to theslicer/demultiplexer 111. In this embodiment the I/O circuits 310receive the input data stream D from a data source (not shown) andprovide the N sub-streams (D₀ . . . D_(N−1)) to the demodulators 112.

In one embodiment, the combiner 161 described above with respect to FIG.1 is implemented using a computing device such as the computing device300 of FIG. 3. Specifically, the processor 320 executes the variousfunctions described above with respect to the combiner 161. In thisembodiment the I/O circuits 310 receive the demodulated sub-streams D₀′,D₁′ and D₂′ from the demodulators 162 (optionally via buffers 166) andprovide the output data stream D′ representative of the input datastream D initially processed by the virtual spectrum aggregatortransmitter 110.

In one embodiment, the optional control module 170 described above withrespect to FIG. 1 is implemented using a computing device such as thecomputing device 300 of FIG. 3.

Although primarily depicted and described as having specific types andarrangements of components, it will be appreciated that any othersuitable types and/or arrangements of components may be used forcomputing device 300. The computing device 300 may be implemented in anymanner suitable for implementing the various functions described herein.

It will be appreciated that computer 300 depicted in FIG. 3 provides ageneral architecture and functionality suitable for implementingfunctional elements described herein and/or portions of functionalelements described herein. Functions depicted and described herein maybe implemented in software and/or hardware, e.g., using a generalpurpose computer, one or more application specific integrated circuits(ASIC), and/or any other hardware equivalents.

It is contemplated that some of the steps discussed herein as softwaremethods may be implemented within hardware, for example, as circuitrythat cooperates with the processor to perform various method steps.Portions of the functions/elements described herein may be implementedas a computer program product wherein computer instructions, whenprocessed by a computer, adapt the operation of the computer such thatthe methods and/or techniques described herein are invoked or otherwiseprovided. Instructions for invoking the inventive methods may be storedin fixed or removable media, transmitted via a data stream in abroadcast or other signal bearing medium, transmitted via tangible mediaand/or stored within a memory within a computing device operatingaccording to the instructions.

FIG. 4 depicts a flow diagram of a method according to one embodiment.Specifically, the method 400 of FIG. 4 is suitable for processing a datastream D for transmission, such as described above with respect to FIG.1.

At step 410, the data stream including data from one or more customersis received, such as by the virtual spectrum aggregated transmitter 110.

At step 420, the received data stream is sliced into N sub-streams,where each sub-streams is associated with a respective spectralfragment. Referring to box 425, the slicing of data streams intosub-streams may be performed using any of the following criteria, aloneor in any combination: per customer, per fragment, for data type, fixedsize, variable size, combination of various slicing methods and/or othercriteria.

At step 430, each of the sub-streams is modulated using a respectivemodulator. Referring to box 435, demodulators may be optimized for datatype, optimized for channel conditions, they share commoncharacteristics, they have various/different characteristics and so on.

At optional step 440, where one or more modulated sub-streams are to betransmitted using the same transponder or transmission channel, thesemodulated sub-streams are combined.

At step 450, the modulated sub-streams are up converted and transmitted.Referring to box 455, the up conversion/transmission process may bewithin the context of a satellite communication system, microwavecommunication system, wireless communication system/channel or othermedium.

FIG. 5 depicts a flow diagram of a method according to one embodiment.Specifically, the method 500 of FIG. 5 is suitable for processing one ormore received sub-streams, such as described above with respect to FIG.1.

At step 510, one or more modulated sub-streams are received and downconverted. Referring to box 515, one or more modulated sub-streams maybe received via a satellite communication system, wireless communicationsystem, wireless communication system/channel or other medium.

At step 520, any sub-streams previously combined at the transmitter areseparated to provide individual sub-streams, and at step 530 each of theindividual sub-streams is demodulated using a respective appropriatedemodulator.

At step 540, one or more of the demodulated sub-streams are selectivelydelayed so that the resulting demodulated data streams may be temporallyaligned.

At step 550, the demodulated and selectively delayed sub-streams arecombined to provide a resulting data stream such as a data stream D′representative of an input data stream D initially processed by thevirtual spectrum aggregator transmitter.

FIG. 6 depicts a flow diagram of a method according to one embodiment.Specifically, the method 600 of FIG. 6 is suitable for configuringvarious transmitter and receiver parameters in accordance with thevarious embodiments.

At step 610, a request is received for the transmission of customerdata. Referring to box 615, the request may provide a specifiedbandwidth, a specified data rate, a specified data type, specifiedmodulation type and/or other information describing the bandwidth and/orservice requirements associated with the customer data transmissionrequest.

At step 620, a determination is made as to the spectrum allocationsuitable for satisfying the customer data transmission request.

At step 630, an optional determination is made as to whether anyspecific spectrum related criteria is suitable for satisfying thecustomer data transmission request. Referring to box 635, such spectrumrelated criteria may include a minimum bandwidth block size, arequirement for contiguous bandwidth blocks and/or other criteria.

At step 640, available spectrum fragments are identified. Referring tobox 645, the identification of available spectrum fragments may be madewith respect to an allocation table, a management system and/or othersource of such information. In one embodiment, an allocation tabledefines the spectral allocation associated with each customer served bya satellite communications system; namely, the bandwidth allocation ofeach customer, the transponder(s) supporting the bandwidth, thesatellite(s) supporting the transponder(s) and so on. Additionally,available spectrum fragments are defined in terms of size and spectralregion for each transponder of each satellite.

At step 650, available spectrum fragments are allocated to satisfy thecustomer data transmission request. Referring to box 655, the availablespectrum fragments may be allocated as available, optimized for thecustomer, optimized for the carrier, optimized to reduce spectrumfragment count, optimized to provide resiliency or redundancy, and/oroptimized based on other criteria.

At step 660, transmitter/receiver systems are configured to provide thecorrect number and type of modulators/demodulators to support thecustomer data transmission request and adapt to any changes to spectrumfragment allocations for the requesting customer and/or other customers.That is, based upon optimization and/or other criteria, it may beappropriate to modify the spectral fragment allocations of multiplecustomers to optimize in favor of a particular customer, serviceprovider and the like.

At step 670, billing data, service agreements and the like are updatedas appropriate. At step 680, system configuration, provisioning and/orother management data is updated.

In various embodiments, spectral fragment available on differentsatellite transponders and/or different satellites are aggregated toform a virtual contiguous block. In other embodiments, the entirebandwidth of multiple transponders is used to support high data-ratepipes (e.g., OC-3/12c) over satellite links.

FIGS. 7-9 depict block diagrams of communication systems according tovarious embodiments. Each of the various components within thecommunication systems depicted in FIGS. 7-9 operates in substantiallythe same manner as described above with respect to correspondingcomponents within the communication system of FIG. 1. For example, ineach of the embodiments of FIGS. 7-9, an input data stream D is receivedby a virtual spectrum aggregated transmitter 110, where it is processedby a slicer/de-multiplexer x11 to provide N sub-streams (D₀ . . .D_(N−1)), where each of the N sub-streams is modulated by respectivemodulator x12. Other differences and similarities between the variousfigures will now be described more detail.

FIG. 7 depicts a single transponder embodiment in which a singletransponder is used to transport each of a plurality of data streamsdenoted as streams A, B, C and D. FIG. 7A depicts an uplink portion ofthe system, while FIG. 7B depicts a downlink portion of the system.

Referring to FIG. 7A, data streams A, B and C are modulated byrespective modulators 712 to produce respective modulated streams whichare then combined by a first signal combiner 113 ₁ to provide a combinedmodulated signal ABC.

Data stream D is processed by a slicer/de-multiplexer 711 to provide Nsub-streams (D₀ . . . D_(N−1)) which are then modulated by respectivemodulators 712 (i.e., modulators 712 ₀, 712 ₁ and 712 ₂) to providecorresponding modulated signals to be carried by respective spectralfragments S₀, S₁ and S₂. The corresponding modulated signals arecombined by a second signal combiner 713 ₂ to provide a combinedmodulated signal DDD, which is combined with modulated signal ABC by athird signal combiner 713 ₃. The resulting combined modulated signalsare converted by an up converter 714 to produce a carrier signal C whichis amplified by a power amplifier 720 and transmitted towards asatellite 740 via a satellite uplink 730.

Referring to FIG. 7B, satellite 740 transmits a modulated carrier signalincluding the modulated streams A through D to satellite downlink 750,which propagates the signal to a down-converter, 765. The down-convertedsignal is processed by a frequency de-multiplexer 164 ₃ which operatesto separate the signal into the ABC and DDD signal components.

The ABC signal components are separated by a second frequencyde-multiplexer 764 ₁ to recover the modulated signals and thendemodulated by respective demodulators 752.

The DDD signal components are separated by a third frequencyde-multiplexer 764 ₂ to recover the modulated signals which aredemodulated by respective demodulators 752.

The demodulated sub-streams D₀′, D₁′ and D₂′ are processed by a combiner761 to produce an output data stream D′ representative of the input datastream D. It is noted that each of the demodulators 162 operates in amanner compatible with its corresponding modulator 112.

FIG. 8 depicts a dual transponder embodiment in which a firsttransponder is used to transport each of a plurality of data streamsdenoted as streams A, B, and C, as well as two of three sub-streamsassociated with a data stream D, while a second transponder is used totransport each of a plurality of data stream denoted as E and F, as wellas the third sub-stream associated with the data stream D. FIG. 8Adepicts an uplink portion of the system, while FIG. 8B depicts adownlink portion of the system.

Referring to FIG. 8A, data streams A, B, C, E and F are modulated byrespective modulators 812 to produce respective modulated streams.

Data streams E and F are modulated by respective modulators 812 toproduce respective modulated signals.

Data stream D is processed by a slicer/de-multiplexer 711 to provide Nsub-streams (D₀ . . . D_(N−1)) which are then modulated by respectivemodulators 712 (i.e., modulators 712 ₀, 712 ₁ and 712 ₂) to providecorresponding modulated signals to be carried by respective spectralfragments S₀, S₁ and S₂.

The modulated signals associated with data streams A, B and C arecombined by a first signal combiner 813 ₁ to provide a combinedmodulated signal ABC.

The modulated signals associated with sub-streams D₀ and D₁ are combinedby a second signal combiner 813 ₂ to provide a combined modulated signalD₁₂.

The combined modulated signals produced by the first 813 ₁ and second813 ₂ signal combiners are then combined by a third signal combiner 813₃ and converted by a first upconverter 814 ₁ to produce a first carriersignal C1.

The modulated signals associated with sub-stream D₃ and streams E and Fare combined by a fourth signal combiner 813 ₃ and converted by a secondupconverter 814 ₂ to produce a second carrier signal C2.

The C1 and C2 carrier signals are combined by a fourth signal combiner,813 ₄, amplified by a power amplifier, 820, and transmitted towards asatellite, 840, via respective transponders (A and B) of a satelliteuplink 830.

Referring to FIG. 8B, satellite 840 transmits the two modulated carriersignals including the modulated streams A through F via respectivetransponders (A and B) to satellite downlink 850, which propagates thesignal to a down-converter 865. The down-converted signal is separatedinto its two carrier signals by frequency demultiplexer 864 ₄. The twocarrier signals are processed using various demultiplexers in 864,demodulators in 862 and combiner 861 to produce the various output datastreams A′ through F′ representative of the input data stream A throughF.

FIG. 9 depicts a dual satellite embodiment in which one satellite (940₁) is used to transport a plurality of data streams denoted as streamsA, B, and C, as well as two of the three sub-streams associated withdata stream D.A second satellite (940 ₂) is used to transport aplurality of data streams denoted E and F as well as the thirdsub-stream associated with data-stream D. FIG. 9A depicts an uplinkportion of the system while FIG. 9B depicts a downlink portion of thesystem.

Referring to FIG. 9A, data streams A, B, C, E and F are processed insubstantially the same manner as described above with respect to FIG.8A, except that the two carrier signals are not combined for transportvia respective transponders of a single satellite. Rather, FIG. 9 showstwo carrier signals amplified by separate power amplifiers (920 ₁ and920 ₂) and transmitted to satellites 940 ₁ and 940 ₂, respectively,using uplinks 930 ₁ and 930 ₂.

Referring to FIG. 9B, the two satellites 940 transmit their respectivemodulated carrier signals including modulated streams A through F viarespective downlinks 950, which are then fed to respectivedown-converters 965. The two down-converted carrier signals areprocessed using de-multiplexers (964), demodulators (962) and a combiner(961) to produce the output data streams A′ through F′ representative ofthe input data streams A through F.

FIG. 10 depicts a high-level block diagram of a slicer/de-multiplexersuitable for use in the various embodiments described herein.Specifically, the slicer/de-multiplexer 1000 of FIG. 10 comprises apacket encapsulator 1010, a master scheduler 1020 including a buffermemory 1022, and a plurality of slave schedulers 1030 including buffermemories 1032.

The packet encapsulator 1010 operates to encapsulate packets receivedfrom data-stream D into a packet structure having a predefined ornormalized format. While various encapsulating packet formats may beused, it is important that the combiner at a downlink side of a systembe configured to combine packets according to the encapsulating formatused by the slicer/de-multiplexer at an uplink side of the system.

In one embodiment, encapsulating packets comprise 188 byte packetshaving a 185-byte payload section and a three-byte header section. Thepacket encapsulator 1010 extracts a sequence of 185 byte portions fromthe original data stream D, and encapsulates each extracted portion toform encapsulating packet (EP). The header portion of each encapsulatingpacket stores a user sequence number associated with payload data suchthat the sequence of 185 byte portions of the data stream may bereconstructed by a combiner, such as described above with respect to thevarious figures.

In one embodiment, the user sequence number comprises a 14-bit numberthat is continually incremented and used to stamp encapsulated packetsprovided by the packet encapsulator 1010. In one embodiment, the headerportion of the packet provided by the packet encapsulator 1010 comprisesa first byte storing 47 hexadecimal (i.e. 47 h), followed by 2 zerobits, followed by 14 bits associated with the user sequence number.

A larger sequence number field (e.g., 24 or 32 bits) may be used whenthe aggregate data rate being transported is higher. The size of thesequence number field is related to the amount of buffering that takesplace at the receiving combiner element described in various figuresabove. The size of the buffer, in turn, is related to the ratio of thelargest sub-stream bandwidth to the smallest sub-stream bandwidth. Thus,various embodiments may adjust the sequence number field size (and theresulting overhead) based on total aggregate bandwidth and/or the ratioof the highest to smallest bandwidth sub-streams.

In various embodiments, more or fewer than 188 bytes are used toconstruct encapsulating packets. In various embodiments, more or fewerthan three bytes are used to construct encapsulating packet headers. Forexample, by allocating additional header bits to the user sequencenumber a larger user sequence number may be used. In this case, thelikelihood of processing at a receiver two encapsulating packets havingthe same sequence is reduced.

In the embodiments described herein, the fixed packet size of 188 bytesis used for the encapsulating packets. However, in various alternateembodiments different fixed-sized packets and/or different variablesized packets may be used for different sub-streams as long as suchpacket sizes are compatible with the input interfaces of the respectivemodulators used for those sub-streams.

The master scheduler 1020 routes encapsulated packets to the variousslave schedulers 1030. The slave schedulers 1030 in turn route theirpackets to respective output ports of the slicer/demultiplexer, therebyproviding respective sub-streams to, illustratively, modulators or othercomponents.

Generally speaking, each slave scheduler 1030 accepts packets conformingto the bandwidth of the spectral fragment assigned to that scheduler.Thus, the slave scheduler servicing a 1 MHz spectral fragment channelaccepts packets at a data rate approximately 1/10 that of a slavescheduler serving a 10 MHz spectral fragment or region.

The master scheduler 1020 communicates with the slave schedulers 1030 toidentify which slave scheduler 1030 is (or should be) capable ofreceiving the next encapsulated packet. Optionally, the master scheduler1020 receives status 20 and other management information from the slaveschedulers 1030, and some of this status information may be propagatedto various management entities (not shown).

In one embodiment, the slave schedulers 1030 provide a control signal tothe master scheduler 1020 indicative of an ability to accept the packet.In one embodiment, the master scheduler 1020 allocates packets to theslave schedulers 1030 in a round robin fashion. In one embodiment, wherecertain transmission channels or spectral regions are preferred basedupon customer and/or service provider requirements, the allocation ofencapsulated packet by the master scheduler 1020 is weighted in favor ofproviding more encapsulated packets to those slave schedulers 1030servicing the preferred transmission channels.

In one embodiment, each of the slave schedulers is associated with apredefined bandwidth or other indicators of channel capacity associatedwith the corresponding spectral fragment. In this embodiment, the masterscheduler 1020 routes packets according to a weighting assignment foreach slave scheduler 1030.

Generally speaking, the master scheduler routes packets according to oneor more of a random routing algorithm, a round robin routing algorithm,a customer preference algorithm and a service provider preferencealgorithm. Such routing may be accommodated by associating a weightingfactor with each modulator, spectral fragment, communications channel(e.g., transponder, microwave links, wireless channel etc.) and so on.For example, a preferred spectral fragment may comprise a fragmenthaving a minimum or maximum size, a fragment associated with arelatively low error or relatively high error channel, a fragmentassociated with a preferred communications type (e.g., satellite,microwave link, wireless network and so on), a fragment associated witha preferred customer and the like. Other means of weighting channels,communication systems, spectral regions and so on may also be usedwithin the context of the various embodiments.

FIG. 11 depicts a flow diagram of a method according to one embodiment.At step 1110, packets are received from data stream D. At step 1120,received packets are encapsulated. Referring to box 1125, the packet maycomprise 185 byte payload and three byte header packets. Other headerformats with a different sequence number field size and/or additionalcontrol information may be used within the context of the presentembodiments.

At step 1130 the encapsulated packets are buffered by, illustratively,the master scheduler 1020, a separate buffer (not shown) within thepacket encapsulator 1010 and so on.

At step 1140, encapsulator packets are forwarded (or caused to beforwarded) to the slave schedulers 1030 by the master scheduler 1020.

In the various embodiments described herein, each encapsulated packet iscoupled to a respective modulator as part of a respective sub-stream.However, in embodiments adapted to provide increased data resiliencyand/or backup, encapsulated packets may be coupled to multiplemodulators as part of multiple respective sub-streams. In theseembodiments, the sequence number associated with the encapsulated packetremains the same.

In these embodiments, a receiver will process the first encapsulatedpacket (or error-free encapsulated packet) having the appropriatesequence number and ignore other packets having the same sequencenumber. That is, when re-ordering encapsulating packets at the receiver,those encapsulating packets having a sequence number matching a sequencenumber of a recently ordered encapsulating packet are discarded. Sincesequence numbers are cyclical or repeated (e.g., every 16,384encapsulating packets in the case of a 14-bit sequence number), anencapsulating packet having the same sequence number of encapsulatingpacket processed several thousand packets ago is likely a duplicate ofthat previously processed encapsulating packet and, therefore, should bedropped or discarded as being redundant.

Various embodiments described herein provide dynamic spectrumaggregation of disjoint blocks of spectrum such that spectrum may beadded to or subtracted from existing spectrum allocations as customerbandwidth requirements change. Additionally, small or orphaned spectrumblocks (i.e., those spectrum blocks too small to generally be useful)may be virtually combined to form larger blocks of bandwidth.

The above-described embodiments provide a number of advantages,including improved system resiliency since the loss of any one spectralfragment will likely not cause a complete loss of service. In addition,when spectral fragments are mapped across multiple transponders, theloss of any one transponder does not result in a complete loss ofservice; rather, a graceful degradation of service is provided.Older/existing schemes utilizing contiguous spectrum are capable ofusing only one transponder which becomes a potential single point offailure.

Various benefits of the embodiments include significantly higherspectral usage efficiency as well as the ability to use orphanedspectral fragments that are too small to use otherwise. The variousembodiments are applicable to satellite applications, point-to-pointwireless links such as those used in bent-pipe SatCom applications,wireless backhaul infrastructure such as provided using microwave towersand so on.

The various embodiments provide a mechanism wherein bandwidth may beallocated by “appending” additional blocks of bandwidth to thosebandwidth blocks already in use, thereby facilitating a“pay-as-you-grow” business model for service providers and consumers.

In various embodiments, a single transponder in a satellite system isused to propagate a carrier signal including a plurality of modulatedsub-streams, each of the modulated sub-streams occupying its respectivespectral fragment region. In other embodiments, multiple carrier signalsare propagated via respective transponders.

In various embodiments, a single microwave link within a microwavecommunication system is used to propagate a carrier signal including aplurality of modulated sub-streams, each modulated sub-stream occupyingits respective spectral fragment region. In other embodiments, multiplecarrier signals are propagated via respective microwave links.

In various embodiments, a single wireless channel within a wirelesscommunication system is used to propagate a carrier signal including aplurality of modulated sub-streams, each modulated sub-stream occupyingits respective spectral fragment region. In other embodiments, multiplecarrier signals are propagated via respective wireless channels.

While the foregoing is directed to various embodiments of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof and those skilled in theart can readily devise many other varied embodiments that stillincorporate these teachings. As such, the appropriate scope of theinvention is to be determined according to the claims, which follow.

1. A method, comprising: dividing a data stream into a plurality ofsub-streams, each of said sub-streams associated a respective spectralfragment and having a data rate compatible with a bandwidth of therespective spectral fragment; modulating each of the sub-streams toprovide a modulated signal adapted for transmission via the respectivespectral fragment; and upconverting said modulated signals ontorespective spectral fragments of at least one carrier signal; whereinthe sub-streams included within the upconverted modulated signals areadapted to be demodulated and combined at a receiver to recover therebydata stream.
 2. The method of claim 1, further comprising combining twoor more of the modulated sub-streams to form respective combinedsub-streams, each of said combined sub-streams being modulated onto amodulated signal adapted for transmission via a spectral fragment havinga bandwidth compatible with the total effective data rate of combinedsub-streams.
 3. The method of claim 1, further comprising transmittingsaid carrier signals via respective channels within a communicationssystem.
 4. The method of claim 3, wherein each of said one or morecarrier signals is supported by a respective transponder within asatellite communications system.
 5. The method of claim 3, wherein eachof said one or more carrier signals is supported by a respectivemicrowave link within a microwave communications system.
 6. The methodof claim 3, wherein each of said one of more carrier signals issupported by a respective wireless channel within a wirelesscommunications system.
 7. The method of claim 1, wherein said dividing adata stream into a plurality of sub-streams comprises: encapsulatingsequential portions of said data stream into payload portions ofrespective encapsulating packets, each of said sequential portions ofsaid data stream being associated with a respective sequence numberincluded within a header portion of the respective encapsulating packet;and including each encapsulating packet within a respective sub-stream.8. The method of claim 1, wherein said dividing a data stream into aplurality of sub-streams comprises: encapsulating sequential portions ofsaid data stream into payload portions of respective encapsulatingpackets, each of said sequential portions of said data stream beingassociated with a respective sequence number included within a headerportion of the respective encapsulating packet; and including eachencapsulating packet within one or more of said sub-streams.
 9. Themethod of claim 7, wherein said sequence number is represented by afield having at least 14 bits.
 10. The method of claim 7, wherein saidencapsulating packet header further includes a hexadecimal 47 in a firstbyte.
 11. The method of claim 1, further comprising: receiving each ofthe modulated sub-streams via respective spectral fragments;demodulating each of the modulated sub-streams; combining thedemodulated sub-streams to recover the data stream.
 12. The method ofclaim 11, wherein combining the demodulated sub-streams to recover thedata stream comprises: ordering encapsulating packets received via oneor more sub-streams according to their respective sequence numbers; andextracting sequential portions of said data stream from said orderedencapsulating packets to recover thereby said data stream.
 13. Themethod of claim 12, further comprising discarding encapsulating packetshaving a sequence number matching the sequence number of a recentlyreceived encapsulating packet.
 14. Apparatus, comprising: a splitter,for dividing a data stream into a plurality of sub-streams, each of saidsub-streams associated a respective spectral fragment and having a datarate compatible with a bandwidth of the respective spectral fragment; aplurality of modulators, each modulator configured to modulate arespective sub-stream to provide a modulated signal adapted fortransmission via the respective spectral fragment; and at least oneupconverter, for upconverting said modulated signals onto respectivespectral fragments of at least one carrier signal; wherein thesub-streams included within the upconverted modulated signals areadapted to be demodulated and combined at a receiver to recover therebydata stream.
 15. The apparatus of claim 14, wherein said splittercomprises: an encapsulator, for encapsulating sequential portions ofsaid data stream into payload portions of respective encapsulatingpackets, each of said sequential portions of said data stream beingassociated with a respective sequence number included within a headerportion of the respective encapsulating packet; and a master scheduler,for selectively routing encapsulated packets towards the demodulators.16. The apparatus of claim 15, wherein said splitter further comprises aplurality of sub schedulers, each of said sub schedulers adapted toroute packets received from the master scheduler toward a respectivemodulator.
 17. The apparatus of claim 15, wherein said master schedulerroutes packets according to one of a random routing algorithm and around robin routing algorithm.
 18. The apparatus of claim 15, whereinsaid master scheduler routes packets according to one of a customerpreference algorithm and a service provider preference algorithm,wherein each sub-stream is associated with a respective weight.
 19. Theapparatus of claim 18, wherein the respective weight of a sub-stream isdefined by one or more of a preferred spectral fragment, a preferredspectral fragment type, the preferred communication channel, a preferredcommunication channel type, a preferred traffic type and a preferredcustomer.
 20. A computer readable medium including software instructionswhich, when executed by a processer, perform a method comprising:dividing a data stream into a plurality of sub-streams, each of saidsub-streams associated a respective spectral fragment and having a datarate compatible with a bandwidth of the respective spectral fragment;modulating each of the sub-streams to provide a modulated signal adaptedfor transmission via the respective spectral fragment; and upconvertingsaid modulated signals onto respective spectral fragments of at leastone carrier signal; wherein the sub-streams included within theupconverted modulated signals are adapted to be demodulated and combinedat a receiver to recover thereby data stream.
 21. A computer programproduct, wherein a computer is operative to process softwareinstructions which adapt the operation of the computer such thatcomputer performs a method comprising: dividing a data stream into aplurality of sub-streams, each of said sub-streams associated arespective spectral fragment and having a data rate compatible with abandwidth of the respective spectral fragment; modulating each of thesub-streams to provide a modulated signal adapted for transmission viathe respective spectral fragment; and upconverting said modulatedsignals onto respective spectral fragments of at least one carriersignal; wherein the sub-streams included within the upconvertedmodulated signals are adapted to be demodulated and combined at areceiver to recover thereby data stream.